費用を

the cost

→ 費用
phrase Rare #29,415
the cost 費用 means expenses or costs, and を marks it as the object of the verb. The phrase usually appears as part of a larger sentence.
JA: 旅行の費用を計算しています。
EN: Please let me know the cost.

費用を全部一緒にしよう

Let's pool all the costs together.

日本行きの費用を大学出してくれたんです

The university paid for my trip to Japan.

その費用をお知らせ下さい

Please let me know the cost.